The present inventive subject matter relates to the art of electric motors. It is particularly applicable to stepper motors driven by chopping amplifiers, e.g., as are commonly implemented in printers, copiers, scanners, facsimile machines, xerographic devices, image reproduction and/or marking engines, etc., and it will be described with particular reference thereto. However, application is also found in connection with other devices and/or implementations.
In image reproduction and/or marking engines such as printers, copiers, scanners, facsimile machines, xerographic devices, etc., direct current (DC) electric motors, and in particular stepper motors, are commonly employed to carry out various motorized tasks, e.g., paper transporting, moving a print head, carriage assembly or other object, or other similar tasks. However, in certain instances the motor may malfunction or deviate from otherwise normal operation. For example, the motor may become stalled or stopped due to some physical obstruction or other impediment. Alternately, the load on the motor may vary from normal operating conditions, e.g., due to a failing or bad bearing, and hence the motor speed may vary from normal operating conditions. In such instances, diagnostic evaluation of the motor's operational state is often advantageous to determine where in fact the fault lies. Whether or not the motor is stalled and/or the motor's speed are of interest in diagnosing such problems.
In some instances, separate and/or independent detectors, e.g., an optical encoder or flag and sensor, are used to monitor the position and/or speed of the motor and/or the object being moved thereby. Such implementations however can be disadvantageous as the separate independent detectors present added production cost and/or other drawbacks that normally attend the use of additional components.
The present inventive subject matter contemplates a new and improved electric motor implementation and/or method for detecting an operational state of the of the same that overcomes the above-mentioned limitations and others.